Process for preparing 2,6,6-trimethyl 1-alkoxycarbonyl-2,4-cyclohexadienes

ABSTRACT

Process for preparing lower alkyl esters of 2, 6, 6-trimethyl 1 - carboxy - 2, 4 - cyclohexadiene comprises reacting an allyl quaternary phosphonium salt with a lower alkyl alpha isopropylidene acetoacetate in the presence of a strong base. These esters are useful in synthesis of unsaturated alicyclic ketones for application as perfuming and flavoring agents.

UnitedStates Patent [1 1 Btichi et al;

PROCESS FOR PREPARING 2,6,6-TRIMETIIYL l-ALKOXYCARBONYL-2,4- CYCLOIIEXADIENES Inventors: George II. Buchi; Hans Wuest, both of Cambridge, Mass.

Assignee: Firmenich S.A., Geneva,

Switzerland Filed: Aug. 16, 1972 Appl. No.: 281,220

Foreign Application Priority Data Aug. 17. i971 Switzerland 12119/71 US. Cl 260/468 L; 131/17; 252/522; 260/348 A; 260/408 K; 260/544; 260/546; 260/586 R; 260/598; 260/631 S; 426/17 S Int. Cl. C07c 67/06; C07c 69/74 Field of Search 260/468 L June 17, 1975 [56] References Cited UNITED STATES PATENTS 2,933,506 4/l960 Osloff 260/343.2

OTHER PUBLICATIONS Organic Reactions, VoL 14, p. 352 (1965). House, Modern Synthetic Reactions, pp. 245-256 (1904). Pines et al., J. A. C. S-82, 2471 (1960).

Primary Examiner-Robert Gerstl Attorney, Agent, or Firm-Pennie & Edmonds 7 Claims, No Drawings PROCESS FOR PREPARING 2,6,6-TRIMETHYL l-ALKOXYCARBONYL-2,4-CYCLOHEXADIENES SUMMARY OF THE INVENTION The invention relates to a new process for the preparation of unsaturated cycloaliphatic ketones having the formula COCH2- CH cH containing either two non-conjugated double bonds in the land 4- positions, or two conjugated double bonds in the land 3-, (exocyclic) 2- and 3-, or (endocyclic) 2- and 4-positions of the ring, the double bonds being represented by the dotted lines, which process comprises acylating organo-metallic compounds having the formula CH2=CH-CH2ME wherein ME represents a metal function, such as Li, Zn, Cd or Mg-halogen, by means of compounds having the formula CO-O-ulkyl Illa wherein the dotted lines have the meaning indicated above.

BACKGROUND OF THE INVENTION One of the main objects of the aromatisation of foodstuffs for instance is to restore the original quality and nature of the flavour, aroma and taste of a given foodstuff material. Very often in fact the organoleptic properties of foodstuffs particularly diminish or are somehow modified in the course of the processes of freezing and storage, or during the modifications, such as cooking or baking, to which the foodstuffs are subjected in 5 order to yield an edible material.

In the past the aromatisation was mainly achieved by using materials of natural origin. Nowadays, however, synthetic chemical compounds are used at an ever increasing rate. Said compounds possess the advantage of being available very often in unlimited quantities and at prices lower than those of the natural materials. Moreover, due to the fact that the flavouring character of a natural material is the result of the overall effect determined by the combination and interaction of each of its constituents, the effects achieved by said natural material are very often not as well reproducible as those obtained by the use of the pure synthetic compounds.

In the field of perfumery the man in the art has to solve a similar problem in attempting to constitute the olfactive notes of certain natural essential oils or extracts. The perfumers creativity however is continually boosted by the finding of new synthetic compounds, the organoleptic properties of which will enable him to introduce unprecedented olfactive characters or nuances into new phantasy perfume compositions.

As a consequence, the problem that the chemical industry has to solve is to satisfy the increasing demand of new organoleptically interesting chemicals in order to better suit the specific needs of flavourists and perfumers.

It is known in the art that compounds of general formula wherein the side chain attached at position 1 of the ring contams one double bond in position 2 or 3 the ring contains one endocyclic double bond in position 1 or 2, or one exocyclic double bond in position 2, or two conjugated double bonds in position 1 and 3;

n is zero or one;

R, R and R all represent hydrogen, or one of them an alkyl group and the others hydrogen; and R, R R and R all represent hydrogen, or one of them an alkyl group and the others hydrogen possess valuable organoleptic properties [see e.g. Swiss Pat. No. 509,399 and German Offenlegungsschrift No. 2,022,216]. The present invention provides a similar class of compounds as well as processes for preparing them.

It has now been found in fact that most of the compounds of formula I and certain of their related derivatives, forming together a class of compounds of general formula containing a double bond in the 2- or 3'- position of the side chain and either two conjugated double bonds in the (endocyclic) 2- and 4-, or (exocyclic) 2- and 3- positions of the ring, or two non-conjugated double bonds in the land 4- positions of the ring, and wherein n stands for the integers l or 2, possess interesting organoleptic properties and accordingly they can be used as flavouring ingredients for modifying, enhancing or improving the Organoleptic properties of foodstuffs for men and animals, beverages, pharmaceutical preparations and tobacco products, and for the preparation of artificial flavouring compositions, and/or as perfuming agents for the preparation of perfumes and perfumed products.

Although the chemical structure of said new compounds is closely related to that of the known above mentioned cycloaliphatic ketones, we have surprisingly found that the olfactive and flavouring characters of the presently disclosed compounds are sensibly different from those possessed by the known derivatives. This fact confirms once more the character of unpredictability which is related to the phenomena of olfaction and tast perception. It has in fact to beunderlined that in spite of the number of theories which have been put forward in order to understand the detection of the specific signaling obtained in the presence or in the ab-' sence of a given chemical, in the present state of our knowledge we have to admit that no theoretical explanation enables-to predict with certainty the odour or taste of a chemical compound [see e.g.: G. Ohloff, La Recherche, 2[l8], 1068 (1971); Mole-cular Structure and Organoleptic Quality, S.C.I. Monograph No. l (1957)]. In actual experience it is known for instance that the Organoleptic properties of ambrinol of formula a, OH

comprising a double bond at one of the positions indicated by the dotted lines, vary according to the specific position of said double bond in the molecule,-the a-isomer possessing the most pronounced ambra character [seez Helv. Chim. Acta, 42, 2233 (1959)].

The particular position of the double bond as well as its ethylenic steroisomerism in an open chain aldehyde, such as hexenal, have a determining effect on the odour. Pure cis-3-hexenal possesses in fact a very strong fresh green odour whereas trans-2-hexenal possesses a less defined sweet smell ll-lelv. Chim. Acta, 45,

The new cycloaliphatic ketones of the present invention possess a distinct olfactive not reminiscent of the flowers of certain plants suchas those of the family of mignonette with-a characteristic fresh, rosy, green,

heady note. The minty note of ,B-darnascenone," an analogous compound of formula Vlll.

CO-CH:CH-CH [seez Helv. Chim. Acta, 53, 541 (1970)], is still present in the odour of some of the new compounds of the invention, but its character is less harsh, definitely sweeter and it is reminiscent of the typical odour of the aromatic leaves of sage.

It has been found that the new compounds mentioned above increase the strength and the diffusion power of the perfume compositions to which they are added and impart thereto, in many cases, a very natural richness. In some cases, they impart to the products, in which they are incorporated, a taste of red berries and can be used for" improving the taste and the artificial flavour of strawberry, cranberry, cherry, red-currants or analogous compositions. The new ketones can surprisingly be used for increasing the taste and flavour of products such as honey or red wine.

The proportions in which the new compounds can be used in order to produce an interesting odoriferous effeet vary within wide limits. In the preparation of perfume compositions, for example, interesting effects can be obtained by the presence of the new compounds in ratios of about ppm to'5 percent of the total of the composition. Depending on the desired odoriferous effects the'ratios of these ketones can be increased to about 10 percent and even more.

If the new compounds are used as flavouring agents or as additives destined to modify the Organoleptic propertiesof foodstuffs for men and aminals, beverages, pharmaceutical preparations and tobacco, their ratios can also vary within wide-limits.

Interesting flavouring effects can e.g. be obtained by the use of 0.1 to 10 ppm of the new compounds, based on the product'to be flavoured. However, these ratios can be increased beyond 10 ppm and reach 100 ppm if it is desired to obtain special flavouring effects. In the preparation of flavouring compositions by admixture of the new compounds with other flavouring agents the said compounds can be used in ratios of about 0.1 to 15 percent of the total of the composition. In many cases the average of the ratios used lies between 1 and 10 percent of the total weight of the composition. It is to be understood that the limits of the proportions given above do not represent absolute limits; in certain cases where special effects are desired the new compounds can be used in higher or lower concentrations than those mentioned above.

The expression foodstuff" is used in this specifica tion in its broadest sense. It also comprises products suchas coffee, tea and chocolate.

One of the processes of the invention for the preparation of unsaturated alicyclic ketones having the formula 1 comprises acylating organo-metallic compounds having'the formula CHFCH-CH'ZME wherein ME represents a metal function, such as Li, Zn, Cd or Mg-halogen, by means of compounds having the formula wherein the dotted lines have the same meaning as above and the symbol X represents a group which is reactive under the reaction conditions, eg halogen, O- CO-alkyl, O-CO-aryl, O-alkyl or O-aryl.

According to a specific embodiment of the present invention the lithium derivative of 2-propenyl is used as the organo-metallic compound, and an ester of formula CO-O-ulkyl Illa : cyclizution citral Cl-CYCIOC it rul The dehydrogenation can be carried out by first halogenating the cyclohexene ring in the allyl-position and then dehydrohalogenating the product of the said halogenation. Common halogenating reagents, e.g. haloamides such as N-bromosuccinimide, N- bromoacetamide, N-dimethyl-bromohydantoin and their chlorinated analogues, can be used as the haloge-- nating agents.

N-bromosuccinimide is preferably used according to the usual method [see Chem. Rev., 63, 21 (1963)].

The halogenation in the allyl-positions can be carried out in an inert solvent. A chlorinated solvent such as CCl CHCl CH CI dichloroethane, tetrachloroethane and trichloroethylene or a mixture of the said solvents can e.g. be used. The operation is preferably carried out at temperatures comprised between 20 and C.

The dehydrohalogenation can be promoted by organic bases, e.g. tertiary amines such as morpholine, piperidine, diethylaniline or dimethylaniline, and the dehydrohalogenation temperature is comprised between about 100 and C.

According to the invention the compounds of formula llla, wherein the double bonds are in the (endocyclic) 2- and 4- positions of the ring, are prepared by a process which comprises treating an alkyl a-isopropylidene-acetoacetate in an inert organic solvent with a compound resulting from the reaction of a quaternary phosphorus salt having the formula wherein R represents an alkyl or aryl radical and X represents a halogen such as e.g. chlorine, bromine or iodine, or a group such as e.g. C10 or BF with a strong base.

CHO

B-cyclocitrul lA/isomerisalion CHO Y-cyc locirrul CHO uor F- or Y-cyclocitrul III Allyl-triphenyl-phosphonium chloride or bromide are preferably used as the quaternary phosphorus salt, and n-butyl, methylor phenyl-lithium as the strong base.

It has been observed that the nature of the base used as well as the reaction conditions selected have no considerable influence on the yield of the final product obtained. However, it is preferred to prepare the allyl-triphenyl-phosphoniurn chloride or bromide by the reaction of triphenylphosphine with an excess of allyl chloride at reflux temperature (45C). The treatment with a strong base can then be carried out at a temperature combrised between about 20 and about +20C. n-Butyl-lithium is preferably used as the strong base, and the operation is carried out in an inert solvent such as ethers, e.g. ethyl ether, monoglyme, diglyme, dioxan or tetrahydrofuran, or hydrocarbons, e.g. cyclohexane, hexane, benzene or toluene. Ethyl ether and hexane and preferably used.

According to the invention the compounds of formula IIIa, wherein the double bonds are in the land 4- positions of the ring, having the formula CO-O-olkyl IIIu-4 When treating the compounds of formula Illa-1 with an acidic agent there is obtained a mixture comprising in addition to the starting product, the compounds having the formulae CO-O-ul ky I CO-O-alkyl and I 110- III -3 phonic acid, or a hydrogen halide, e.g. hydriodic or hydrochloric acid, can be used as the acidic agent. The reaction is preferably carried out by mixing the compound which must be isomerized with the chosen reagent which is dissolved in an inert solvent, e.g. benzene,

are obtained by a process which comprises isomerizing 5 toluene, cyclohexane or hexane and at a temperature a compound having the formula CO-O-ulltyl IIIcl-l in the vicinity of the boiling temperature of the selected solvent:

The compounds of formula llla can moreover be obtained from isophorone derivatives according to a process which can be illustrated by the following reaction scheme:

/ CO-O-cl kyl CO-O-ul kyl L -H O 9 4-0 I koxycc rbony l i sophorone lreducl i on CO-O-al kyl Vll cis and trans l-H o l l CO-O-ulk l co-olk l CO-O-alltyl lllu-l by means of a basic isomerization agent.

Strong organic bases, e.g. alkali metal alkoxides such as sodium, potassium or lithium methoxide or ethoxide are preferably used as the basic agents.

Illa-2 Illa-3 The first step of the process illustrated above consists in a condensation between the mesityl oxide and an alkyl acetoacetate according to a known technique [see H. Rubinstein, J. Org. Chem., 27, 3886 (1962); J.

The isomerization reaction is preferably carried out D. Surmatis et al., J. Org. Chem., 35, 1053 (1970)].

in an alcoholic medium and at a temperature in the vicinity of the reflux temperature of the chosen solvent.

The reduction of the 4-alkoxycarbonyl-isophorones can be carried out by means of reagents which are known to selectively reduce the carbonyl function to a secondary alcohol function, e.g. mixed hydrides of boron and an alkali metal, e.g. sodium or lithium [see e.g. 1-1.0. House, Modern Synthetic Reactions, Benjamin, Inc., New York (1965)].

The carbinols prepared according to the process described above can be obtained in a pure state by a separation by means of vapour phase chromatography or fractional distillation. However, for economic reasons, it is preferred to proceed to the subsequent dehydration of the mixture of isomers such as it is obtained directly by the described reduction in the presence of an acidic catalyst.

As the acidic dehydration catalyst a strong acid, e.g. phosphoric or sulphuric acid, is the preferred one.

The mixture comprising the cyclic esters 111a, if subjected to fractional distillation or separation by means of vapour phase chromatography, yields the esters in a pure state. The latter can be used as starting products for the preparation of the compounds of formula I ac- 20 cording to one of the processes of the invention, or can be reduced by means of lithium-aluminium hydride to their corresponding alcohols having the formulae CHQOH cHzoH scheme:

The subsequent allyl rearrangement can be carried out in an acidic agent such as an inorganic protonic acid e.g. sulphuric acid [cf. for example Ann. der Chem., 618, 202 (1958)].

According to another process of the invention compounds having the formula CH OH with a basic agent, e.g. with an alkali metal alkoxide, such as potassium tert-butoxide, the ketone of formula CO-O-alkyl 'CO-O-olkyl epoxidution 5 COO-dkyl Vll cis-und trunsrear rcngemenl The preparation of the epoxy derivative as well as its conversion into the corresponding tertiary alcohol can be carried out according to known techniques [cf. in this respect Tetrahedron, 19, 1091 (1963) and J. Org. Chem., 26, 3615 (1961)].

is obtained.

If compound la is treated with an acidic isomerization agent, for example with a protonic acid such as p-toluenesulphonic acid, or a hydrogen halide such as hydriodic acid, or with acidic diatomaceous earth, there is obtained a ketone having the formula The isomerization of the double bond on the side chain is accompanied by a concomitant isomerization of the two conjugated double bonds of the hexadienic ring.

In particular, according to the process of the invention described above ketone Vlb is obtained by the treatment of compounds having the formulae lb V1:

with a basic oracidic isomerization agent.

The same reagents as those mentioned above in connection with the preparation of Vla and Vlb can b used as the isomerization agents.

The said isomerization can be carried out by treating the compound to be isomerized and the reagent in a dissolved form in an inert organic solvent, e.g. an aliphatic or cycloaliphatic hydrocarbon, an aromatic hydrocarbon, a chlorinated hydrocarbon, or an ester or an ether. Tetrahydrofuran is the preferred solvent.

As mentioned above, the class of compounds described in the present specification comprises new compounds. As such, 2 ,6 ,6-trimethyll ethoxycarbonyl-l,4-cyclohexadiene, cis-and trans- 2,6,6-trimethyl-l-[buten-2-oyl]-1,4-cyclohexadiene 2,6,6-trimethyl-l-[buten-3-oyl]-1,4-cyc1ohexadiene cisand trans-2,6,6-trimethyl-1 [buten-2-oyl]-2,4- cyclohexadiene, 2,6,6-trimethyl-1-[buten-3-oyl]-2,4- cyclohexadiene, cisand trans-2-methylene-6,6- dimethyl-1-[buten-2-oyl]-3-cyc1ohexene and 2- methylene-6,6-dimethyl-1-[buten-3-oyl]-3- cyclohexene should be mentioned.

The invention is illustrated in a more detailed manner by the following examples wherein the temperatures are indicated in degrees centigrade.

EXAMPLE 1 Preparation of 2,6,6-trimethy1-1-ethoxycarbony1-2,4- cyclohexadiene, of 2,6,6-trimethy11-ethoxycarbony1- 1,3-cyclohexadiene and of 2-methylene-6,6-dimethyl- 1-ethoxy-carbonyl-3-cyclohexene a. 21 g of 3,3,5-trimethyl-4-ethoxycarbony1-5- cyclohexen-l-one were added dropwise to a suspension of 4 g of boron and sodium hydride in 100 m1 of ethanol, maintained under vigorous stirring and at about 510. The reaction mixture was kept at room temperature overnight, concentrated to one-third of its original volume and neutralized by means of diluted hydrochloric acid.

The organic phase which separated was extracted with ether, and the ethereal extracts were then concentrated to dryness to yield a residue (19 g) which, by preparative vapour phase chromatography, gave cisand trans-3,5,5-trimethyl-4- ethoxycarbonyl-S-cyclohexen-l-ol in a weight proportion of about 3:1 (yield 65 percent).

The two isomers have the following analytical characteristics:

A n 1.4770; d, 1.020 IR 1 3400, 1725 cut NMR 0.94 (6H,s);" 1.22 (3H,t, J=7.5 cps); 1.62

(3H,s); 4.12 (2H); 4.1 (1H); 5.6 (1H) 8 ppm MS :M =212 (7); m/e: 197 (48); 183 (18); 166 (12); 154 (41); 138 (52); 123 109 (41); 98 (68); 83 (52); 69 (36); 55 (32); 43 (59); 29 (81). B n 5 1.4788; d 1.038 IR 3400, 1720 cm NMR:0.9 (3l-1,s); 1.09 (3H,s); 1.22 (3H,t, J=8 cps); 1.65 3l-1,s); 2.23 (1H,m); 4.1 (2H,q, J=7 cps); 5.55 (ll-[,m) 8 ppm MS 212 (5); m/e: 197 (47); 183 (18); 166 (11); 151 (12); 138 (54); 123 (100); 109 (23); 98 (20); 83 (48); 69(27); 55 (21); 43 (48); 29 (55). b. 62 of the mixture of isomers obtained according to the process described sub a. above were mixed with 0.5 g of p-toluenesulphonic acid in 200 ml of benzene and the resulting mixture was treated at boiling temperature in a water separator (2 hours). The reaction mixture was then treated with a diluted aqueous solution of sodium bicarbonate, washed with water until neutral, dried. and distilled. A mixture comprising 2,6,6- trimethyl-1-ethoxycarbonyl-2,4-cyclohexadiene, 2,6,6- trimethyl-1-ethoxycarbonyl-1 ,3-cyclohexadiene and 2-methylene-6,6-dimethyl- 1-ethoxycarbonyl-3-cyclohexene in a weight proportion of about 28 42 30, respectively, was obtained; b.p. 60" /0.0l Torr; 34.2 g.

The mixture of products thus obtained was distilled by means of a spinning band fractionating column and the components of the mixture were separated by means of vapour phase chromatography (column CARBOWAX). 2,6,6-Trimethyl-1-ethoxycarbony1-2,4-cyclohexadiene: n 1.4718; df 0.9550; b.p. about 42/0.2 Torr.

IR 1730, 1660, 1600, 730 cm NMR 1.05 (6H,s); 1.2 (3H,t, J=7.5 cps); 1.72

(3H,s); 2.71 (1H,m); 4.06 (2H,q, J=7 cps); 5.05.75 (31-115 PPm MS :M =194(20);m/e: 194(20); 179(1); 165

(0.5); 151 (1); 133 (1); 121 (100); 107 (30); (40); 91 (22); 77 (12); 65 (5); 53 (4); 65 (5); 53 (4); 39 (8); 19 (28). 2,6 ,6-Trimethyl-l-ethoxycarbonyl-1,3-cyclohexadiene: n 1.4809; df 0.9665.

1R 1720, 1635, 1585, 728 cm NMR: 1.08 (6H,'s); 1.3 (3H,t, J=7 cps); 1.78 (3H,s);

4.15 (2H); 5.78 (2H,s) 8 ppm MS :M =194(30);m/e: 179(4); 165 (2); 149 (36); (7); 121 (100); 106 (98); 91 (35); 77 (15); 65 (5);53 (4); 41 (9); 29 (58).

2-Methylene-6,6-dimethyl-1-ethoxycarbonyl-3 cyclohexene: n 1.4809; df 0.9585 [R 3080, 1725, 1630 and 888 cm" NMR 0.89 (3H,s); 0.98 (3H,s); 1.2 (3H,t, J=7.5 cps 2.88 (1H,s); 4.87 (2H,m); 5.6-6.2 (2H) 8 PP" MS :M =194 (.13);m/e: 179(1); (1); 149 (2); 129 (8); 121 (100); 105 (37); 91 (19);?7 (13);65 (4); 55 (5); 41 (13); 29 (26).

The 3,3,5-trimethyl-4-ethoxycarbonyl-S-cyclohexen l-one used as starting product in the preparation described above can be prepared as follows:

260 g of ethyl acetoacetate were mixed with 200 g of mesityl oxide and 200 g of trifluoroboro-etherate in a vessel cooled externally by water and ice in order to maintain the temperature of the mixture at about 5. The said mixture is maintained at this temperature for 3 days, poured then onto ice (800 g) and neutralized with about 400 g of Na CO Then it was extracted with ether and, after the usual treatments of separation, washing and drying, the combined organic extracts were concentrated. Distillation of the residue (135 g) gave 115 g of the desired product, b.p. 85-90/0.1 Torr, which had a purity of 80 as shown by analysis by means of vapour phase chromatography. The product can subsequently be purified by redistillation.

EXAMPLE 2 Preparation of 2,6,6-trimethyl-l-ethoxycarbonyl-2,4- cyclohexadiene, of 2,6,6-trimethyl-l-ethoxycarbonyl- 1,3-cyclohexadiene and of 2-methylene 6,6-dimethyll -ethoxycarbonyl3-cyclohexene a. g of 3,3,5-trimethyl-4-ethoxycarbonyl-5- cyclohexen-lone [which can be prepared according to the method described in Example 1] in 800 ml of methanol were cautiously mixed with a solution of 24 ml of a 30 solution of H 0 and 6 ml of a 6N solution of NaOH. The reaction mixture, after having been stirred for 2 days at room temperature, was neutralized with a diluted l-lCl solution and the volatile portions were separated by evaporation. Distillation of the residue gave 3 ,3 ,5-trimethyl-4-ethoxycarbonyl-5 ,6-epoxycyclohexanone in a pure state.

B.p 90-5/0.1 Torr; n 1.4673; d 1.081. 1R 1715 cm NMR 0.97 (3H,s); 1.28 (3l-l,s); 1.26 (3H,t, J=7.5 cps); 1.38 (3H,s); 2.21 (2H,s); 2.8 (ll-Ls); 3.03 (1H,s); 4.18 (2H,q, J=7 cps) 5 ppm MS :M =226(5);m/e:21l (2); 197(1); 181 (7); 165(1); 151 (6); 138(7); 119(98); 1l7(100);98 (17); 83 (85); 69 (14); 55 (25); 43 (42); 29 (33). b. 3 g of the epoxy-ketone obtained according to the process described sub a. above, dissolved in 20 ml of methanol, were added dropwise within 60 minutes to a mixture of hydrazine hydrate (6 ml) in ml of methanol maintained at l0 and in a nitrogen atmosphere. The reaction mixture was then maintained at about 0 for one day, poured onto ice and extracted with ether. The combined organic extracts, after having been subjected to the usual treatments of drying and concentration, yielded 3 g of a residue which, by distillation, gave 1.7 g (yield 70 percent) of 1,3,3-trimethyl-2- ethoxycarbonyl-S-cyclohexen-l-ol.

n 32 1.4772; d., 1.031. 1R 3450, 1720 and 722 cm NMR 1.02 and 1.04 (2X3H,s); 1.2 (Bl-Lt, J=7 cps); 1.23 (3l-l,s); 2.57 (ll-Ls); 3.17 (1H,m); 4.08 (2H,q, J=7.5 cps); 5.51 (2l-1,m) 6 ppm MS :M =212 (0.1); m/e: 197 179 (0.1); 167 (9); 151 (50); 139 (3); 121 (90); 101 83 (100); 69 (52); 55 (28); 43 (98); 29 (38).

c. A solution of 4.2 g of alcohol, prepared according to the process described in paragraph b. above, in 50 ml of tetrahydrofuran was diluted with water, and to the homogeneous solution thus obtained, maintained at 10, there were added a few drops of 20 percent H 80 The readtion mixture was allowed to stand at room temperature for 24 hours, neutralized with a diluted aqueous solution of Nal-lCO and extracted with petroleum ether. The combined organic extracts, after washing, drying and concentrating, yielded an oily residue (4 g) which, by separation by means of preparative vapour phase chromatography, gave a mixture of cisand trans-3 ,5 ,5-trimethyl-4-ethoxy-carbonyl-5 cyclohexen-lol. The analytical data of the said compounds are identical with those shown by the carbinols prepared according to the process described in Example 1, paragraph a.

d. The subsequent conversion of the obtained carbinols into 2,6,6-trimethyl- 1 -ethoxycarbonyl-2,4- cyclohexadiene, 2,6,6-trimethyl- 1 -ethoxycarbonyl-l ,3- cyclohexadiene and 2-methylene-6,6-dimethyl-lethoxycarbonyl-3-cyclohexene was carried out according to the same process as that described in Example 1, paragraph b.

EXAMPLE 3 2,6,6-Trimethyl-1-ethoxycarbonyl-2,4-cyclohexadiene Method A. A solution of 1.6 M of n-butyl-lithium (48 ml; 77 millimoles) in hexane was added dropwise to a suspension of allyl-triphenylphosphonium chloride (23.7 g; millimoles) in 350 ml of anhydrous ether maintained at about 510 in a nitrogen atmosphere and under vigorous stirring. Stirring was continued for about 1 hour and a solution of ethyl a-isopropylideneacetoacetate (9.5 g; 56 millimoles) in 50 ml of ether was then added to the reaction mixture. After having allowed the said mixture to stand for 1 hour at room temperature, water was added thereto, and the organic phase was separated. After washing, drying and concentrating, the organic phase yielded a partially crystalline residue.

After evaporation of the volatile portions the residue gave by successive extractions with hexane and purification through a column of aluminium oxide (50 g) 6.55 g of the desired ester (yield 60 B.p. 9318 Torr.

IR 1725, 1660 and 1600 cm UV 270 u (e 4220) MS :m/e: 194 (17); 121 (100); 105 (38).

Method B. A solution of 1.6 M of methyl-lithium in ether (44 ml; 70 millimoles) was added dropwise to a suspension of allyltriphenylphosphonium bromide (28.7 g; millimoles) in 400 ml of hexane maintained at about 510 in a nitrogen atmosphere and under vigorous stirring. The reaction mixture was maintained at room temperature for about 6 hours and then a solution of ethyl a-isopropylidene-acetoacetate (9.5 g; 56 millimoles) in 30 ml of hexane was added thereto dropwise. After having allowed the mixture to stand for one hour at room temperature it was filtered and the thus obtained solid substance was washed with a mixture of hexane and ether (2:1). The combined filtrates were then washed with water, dried and concentrated to yield a residue which was purified on a column filled with aluminium oxide (50 g) according to the method described in section A of this Example. There were thus obtained 7.51 g (69 of the desired ester in a pure state. B.p. /8 Torr.

The ethyl a-isopropylidene-acetoacetate used as starting product in the process described above can be prepared as follows:

To a solution of ethyl diacetyl-acetate maintained at method described in Helv. Chim. Acta, 35, 2280 1952)] in 400 ml of anhydrous ether there were added 110 ml (0.33 mole) of a solution of 3 M methylmagnesium bromide in ether. The reaction mixture was stirred for 24 hours at room temperature. After cooling, 50 ml of acetic acid anhydride were added and the whole was allowed to stand for 2 hours at room temperature, whereupon it was poured into ice-water. After separation, the organic phase was washed with a solution of NaOI-I, then with water, whereupon it was dried (Na SO and concentrated. The subsequent distillation of the residue yielded 16.1 g (63 of ethyl a-isopropylidene-acetoacetate, b.p. 9498/8 Torr. A pure sample was obtained by purification of the said product by chromatography on a column (silica gel and benzene) followed by vapour phase chromatography.

IR 1730, 1700, 1640 and 1615 cm NMR: 1.3 (3H,t, J=7.5 cps.); 1.9 (3H,s); 2.0 (3H,s); 2.15 (3H,s); 4.2 (2H.q, J=7.5 cps) Sppm UV 227 p. (e 7900) MS :m/e: 170 (16); 96 (100); 43 (98).

The allyl-triphenylphosphonium chloride used as starting product in the process described above can be prepared as follows:

52.5 g of triphenylphosphine in 300 ml of allyl chloride were refluxed for 96 hours. A solid crystalline product was obtained, m.p. 22l-227.

IR 2450, 2320, 1635, 1585, 985 and 930 cm" .NMR (CRDl 4.9 (2l-l,d of d, J= and 5 cps);

5.2-5.9 (311); 7.7-8.2 (15H) 8 ppm. Thecorresponding bromide can be prepared according to the method described by H. OVHouse et al., J. Org. Chem., 30, 1061 (1965).

EXAMPLE 4 2,6,6-Trimethyl- 1 -ethoxycarbonyl-l ,4-cyclohexadiene 1.0 g of 2,6,6-trimethyl-l-ethoxycarbonyl-2,4- cyclohexadiene was added to a solution of 0.5 M sodium ethoxide in ethanol, maintained in a nitrogen atmosphere and under vigorous stirring. The reaction mixture was refluxed for 60 minutes, then a few drops of acetic acid were added thereto. After evaporation of the volatile protions, the mixture was extracted with pentane and the combined organic extracts were subjected to the usual treatments of washing, drying (Na S04) and.con centration. Distillation of the thus obtained residue yielded 0.92 g of a mixture 55:45 of the isomers. 2,6,6-trimethyl- 1 -ethoxycarbonyl-2,4- and -1,4-cyclohexadiene. B.p. 92/8 Torr.

An analytical sample was obtained by vapour phase chromatography. 7

IR 1705 and 1640 cm (21:1,s); 4.2 (2l-l,q, J=7 cps); 5.4 (2l-I,m) 8 ppm UV 232 p. (e 1320) MS :m/e: 194 (100); 107 (100); 91 (32).

EXAMPLE 5 2,6,6-Trimethyl-1-[buten-3-oyl]-2,4cyclohexadiene and 2-methylene6,6-dimethyl-1-[buten-3-oyl]-3- cyclohexene 2 ml of a solution of 9.4 g (70 millimoles) of allylphenyl ether in 10 ml of ether were added to a suspension, cooled to 0 and maintained under nitrogen, of 2.4 g (0.35 g-atom) of finely cut lithium in 40 ml of anhydrous tetrahydrofuran. Previouslya few crystals of diphenyl had been added to .thesaid suspension. After the appearance of agreenish colour, the residual solution ofallyl-phenyl ether was added dropwise to the re action mixture maintained at about -l5. Cooling was continued for about 30 more minutes. The resulting solution of allyl-lithium was withdrawn from the reaction vessel by means of a syringe and slowly added to a solution of 2,6,6-trimethyl-1-ethoxycarbonyl-2,4- cyclohexadiene, maintained under stirring, [which can be prepared according to the process described in Example 1] (3.88 g; 20 millimoles) in 40 ml of ether at 60 and in a nitrogen atmosphere. The reaction mixture, after having been heated to room temperature,

was poured into ice water and extracted twice with pentane. The combined extracts were washed with water, dried over anhydrous Na SO and concentrated to yield a residue which, by fractional distillation, gave 3.19 g (84 of trans-2,6,6-trimethyl-1-[buten-3-oyl1- 2,4-cyclohexadiene; b.p. 4143/0.05 Torr.

An analytical sample was prepared by purification by means of chromatography on a column filled with silicic acid and using hexane containing 2 percent of ethyl acetate as the eluant.

IR 1695, 1650, 1590, 990 and 915 cm NMR: 1.0 (3H,s); 1.1 (3H,s); 1.7 (3H,s); 2.6(1H,s);

3.2 (2H,d, J=7 cps); 4.7-6.1 (6H,m) 6 ppm UV 267 p. (e 3900) MS :m/e: 190 (7); 121 (44).

By applying the same procedure as indicated above to the acylation of allyl lithium by 2-methylene-6,6- dimethyl- 1 -ethoxycarbonyl-3-cyclohexene [prepared according to Example 1], there will be obtained 2- methylene-6,6-dimethyl-1-[buten-3-oyl1-3- cyclohexene.

IR 1650-1690, 1590, 970 cm MS :M 190.

EXAMPLE 6 trans-2,6,6-Trimethyll -[buten-2-oyl]-2,4- cyclohexadiene and trans-2-methylene-6,6-dimethyl-1- [buten-2-oyl]-3-cyclohexene 2.46 g of 2,6,6-trimethyl-1-[buten-3-oyl]-2,4- cycloxexadiene [prepared according to the process described in Example 5 where added to a solution of mg of potassium in 40 ml of tert-butanol maintained in a nitrogen atmosphere. After having allowed the reaction mixture to stand for 5 minutes at room temperature,,a few, drops of acetic acid .were added thereto, and the volatile portions were then eliminated by evaporation under reduced pressure. Water was added to the concentrated mixture thus obtained and it was extracted with pentane. After separation, the organic extracts were washed, dried over Na SO evaporated and gave a residue which, by fractional distillation, yielded 1.76 g (72 of'the desired ketone. B.p. 39/0.04 Torr.

IR 1680, 1620, 1590 and 965 cm NMR 0.95 (3H,s); 1.0(3H,s);1.7 (3H,s); 1.8 (31-1,

d of d, .l about 1 and 7 cps); 2.6 (1H,s); 5.27.0 (5H,m) 8 ppm 1 I UV 235 p. (a 10500); 266 (e 4650) MS :m/e: (8); 121=(71);-96(100).'

By applying the same procedure as that indicated above to the isomerization of 2-methylene-6,6- dimethyll -[buten-3-oyl]s3-cyclohexene [prepared according to the process described in Example there will be obtained trans-2-methylene-6,6-dimethyl-l- [buten-2-oyl]-3-cyclohexene.

IR 3080, 1600-1690, 960, 880 cm SM M: 190 NMR 0.90 (311,5); 0.95 (31-1,s); 1.90 (3H, d of d, J=6.5, J ca. 1 cps); 2.00 (2H,m); 3.10 (ll-1,5); 4.80 (1H,s); 5.10 (1H, d, J= cps); 6.05 (1H, d of q, J=16 and J ca. 1 cps); 6.75 (1H, d of q, J=16, J'=6.5 cps) 8 ppm UV A 230 p. (e 24000).

EXAMPLE 7 trans-2,6,6-Trimethyl-1-[buten-2-oyl] l ,3- cyclohexadiene A mixture of 289 mg of trans-2,6,6-trimethyl-l [buten-2-oyl]-2,4-cyclohexadiene [prepared according to the process desdribed in Example 6], 25 mg of p-toluenesulphonic acid and 4 ml of anhydrous benzene were refluxed for 2 hours. The reaction mixture was then diluted with pentane, the conbined organic extracts were washed with a 5 percent solution of sodium bicarbonate and water, dried over M1 80; and concentrated. The resulting oily residue was distilled under reduced pressure (0.1 Torr; at a bath temperature of about 80) to yield 201 mg of a mixture containing 33 of trans-2,6,6-trimethyll -[buten- 2-oyl]-1 ,3- cyclohexadiene.

An analytical sample was obtained by purification by means of preparative vapour phase chromatography. The analytical data were identical with those shown by a sample prepared by a known methods [see for example French Patent No. 1,591,031].

EXAMPLE 8 trans-2,6,6-Trimethyl-1-[buten-2-oyl]-1,3- cyclohexadiene A solution of allyl-lithium in ether [prepared as described in Example 5 from 1.2 g of lithium and 4.7 g of allyl-phenyl ether] was added to a solution of 2.02 g (10.4 millimoles) of 2,6,6-trimethyl-1-ethoxycarbonyl- 1,3-cyclohexadiene in 20 ml of ether at -60. The reaction mixture is treeated in a manner analogous to that described in Example 5 and yielded 1.96 g of a product of b.p. 4446/0.55 Torr. The analysis by means of NMR showed that the thus obtained product comprised trans-1,6,6-trimethyl-1-[buten-2-oyl] and 2,6,- 6-trimethyl-1-[buten-3-oyl1-1,3-cyclohexacliene in a ratio of 1:2, respectively.

By isomerizing the said mixture according to the method indicated in Example 6 by means of a solution of 20 mg of potassium in 30 ml of tert.-butanol there were obtained 1.70 g (86 of the desired product. B.p. 51/0.08 Torr.

1R l665,1630,1610 cm NMR 1.0 (611,5); 1.6 (3H,s); 1.9 (31-l,d of d, J=

about 1 and 7 cps); 2.1 (21-1,d, J== about 2 cps); 5.7-7.l (41-1,m) 8 ppm UV 228 1.4.(6 12000); 255 p. (e 5000); 310 p.

(e 2000) MS :m/e: 190 (19); 121 (100); 69 (62).

EXAMPLE9 2,6,6-Trimethyl-l-ethoxycarbonyl-1,3-cyclohexadiene A mixture of 2.0 g of 2,6,6-trimethyl-1- ethoxycarbonyl-2,4-cyclohexadiene' [prepared according to the process indicated in Example 1], 100 mg of p-toluenesulphonic acid and 25 of anhydrous benzene were refluxed for 4 hours in a nitrogen atmosphere. The resulting solution was diluted with pentane, washed with a 5 percent solution of sodium bicarbonate, then with water, and then dried over Na SO and concentrated.

The resulting residue was distilled to yield a product of b.p. 96/8 Torr, 1.87 g (93 By vapour phase chromatography (silicone) there were obtained three isomeric esters in a ratio by weight of 20 22 58, respectively, represented by the formulae and co-o-c H The said esters have the analytical characteristics which are shown in Example 1.

EXAMPLE l0 trans-2,6,6-Trimethyl-1-[buten-2-oyl1-1 ,4- cyclohexadiene By following the same procedure as that indicated in Example 5 about 1 ml of a solution of 4.7 g (35 millimoles) of allyl-phenyl ether in 5 ml of ether is treated with a suspension of 1.25 g (0.18 g-atom) of lithium in 30 ml of anhydrous tetrahydrofuran. After the appearance of a greenish colour, the residual allyl-phenyl ether solution was added dropwise to the reaction mixture maintained at about 15. Proceeding in the manner described in Example 5, the resulting allyl-lithium solution was withdrawn from the reaction vessel by means of a syringe and slowly added to a solution of 2.03 g (10.4 millimoles) of 2,6,6-trimethyl-1- ethoxycarbonyl-l,4-cyclohexadiene, maintained under stirring [which can be prepared according to the process described in Example 4], in 40 ml of ether at 60 and in a nitrogen atmosphere. The reaction mixture was heated to room temperature, poured into ice water and twice extracted with pentane. The combined extracts were washed with water, dried over Na SO and concentrated. The resulting residue was added in a nitrogen atmosphere to a solution of 50 mg of potassium tert-butoxide in 30 ml of tert-butanol. After having maintained the mixture at room temperature for 10 minutes, a few drops of acetic acid were added thereto, whereupon the volatile portions were evaporated under reduced pressure. Then water was added to the reaction mixture and it was extracted with pentane. The organic extracts were separated, combined and treated according to the usual methods of washing with water, drying over Na SO and concentration. The resulting oil was, purified by chromatography on a column g of silicic acid; hexane/1 percent ethyl acetate).

There were, thus obtained 1.431g (73 of the desired product; b.p. 62/0.15 Torr.

IR (Cl-1G 1675, 1640, 1630, 1615, 975 cm NMR(CC1.,) 1.0 (6H,s); 1.5 (311,5); 1.9 (3H, cl of d, J=l and 7 cps); 2.6 (2H, s broad); 5.3-7.0 (41-1,m) 8 ppm UV (ethanol): 228 (E 12900).

EXAMPLE 11 A base perfume composition for after-shave lotion has been prepared by admixing the following ingredients (parts by weight):

Menthol l Eugenol 50 Coumarine 20 Musconc at 10 20 Phenyl ethyl alcohol I20 Lavender oil 210 Pimento oil 40 Cinnamon oil Synth. bergamot 270 Cyclopentadecanone at 30 Methyl 2-pentyl-3-oxo-cyclopentyl acetate Absolute oak moss l5 Benzyle salicylate 20 lsobutylsalicylate 30 Geranium Bourbon oil 70 Musk ketone 20 Ethyl alcohol 50 in 95 ethyl alcohol By adding to 95 g of the hereinabove given base composition 5 g of Z-methylene-6,6-dimethyl-l-[buten2- oyl]-3-cyclohexene there is obtained a perfume composition possessing a pleasant and fresh woody, leathery note. An analogous effect is observed by adding in the same proportion to the above given base composition 2-methylene-6,6-dimethyl-l-[buten-3-oyl1-3- cyclohexene.

EXAMPLE 12 A base perfume composition has been prepared by admixing the following ingredients (parts by weight):

' in dicthyl phthalate By adding to 90 g of this mixture 10 g of 2,6,6- trimethyl-l-[buten-2-oyl1- l ,4-cyclohexadiene there will be obtained a composition possessing a better diffusion than the base composition. The obtained composition possesses a natural herbal tonality,

an analogous effect is observed by adding in the same proportions given to the above base composition 2,6,6- trimethyl-l-[buten-3-oyl1-1,4-cyclohexadiene.

EXAMPLE l3 Perfume Composition of the Chypre Type A perfume composition of the Chypre" type was obtained by admixing the following ingredients (parts by weight):

Bergamot Sweet orange oil Synthetic neroli Synthetic rose Synthetic jasmin Ylang extra Methylionone Hydroxycitronellal Santal oriental Patchouli Vetyveryl acetate Natural degreased civet, l0 Labdanum ciste absolute, l0 Musk ketone l, l -Dimethyl-6-tert-butyl-4-acetyl-indane Coumarin Trichloromethylphenylcarbinyl acetate Tarragon. l0

Oak moss absolute, 5O Benjoin resinoid, l0 Cinnamic alcohol of Styrax Jasmin absolute Rose absolute Cyclopentadecanolide, l0 Methylnonylacetic aldehyde in ethyl phthalate By adding to 99.5 g of this mixture 0.5 g of a 10 percent solution of trans-2,6,6-trimethyl-l-[buten-2,4- cyclohexadiene there will be obtained a more powerful composition than the basic composition whose diffusion is improved and which presents a very natural richness. Analogous results are obtained by replacing in the above example trans-2,6,6-trimethyll -[buten-2-oyl]- 2,4-cyclohexadiene by 2,6,6-trimethyl-l-[buten-3- oyl]-2,4cyclohexadiene.

EXAMPLE l4 Perfume Composition of the Floral Type A composition of the Floral type is prepared by admixing the following ingredients (parts by weight):

Decanal, l0

Undecylenic aldehyde, l0

Lauric aldehyde, l0 Methylnonylacetic aldehyde, l0 Synthetic lily of the valley Synthetic lilac Synthetic rose Synthetic jasmin Bergamot Tarragon, l0

Ylang extra Synthetic carnation Methylionone Vetiveryl acetate Santalol Oak moss absolute, decolourized, l0 Natural civet, degreased. l0

Lily absolute, l

Orange blossom absolute, l0 Jasmin absolute Rose absolute Musk ketone Trichloromethylphenylcarbinyl acetate Tolu balm absolute, colourless, l0 in dicthyl phthalate By adding to 98 g of this mixture 2 g of a solution of trans-2,6,6-trimethyll buten-2-oyl ]-2,4- cyclohexadiene at 10 in diethylphthalate there will be obtained a more powerful composition than the basic composition whose diffusion is improved and which has a very natural richness. The composition thus obtained possessed a fresh green note with a lifting character.

Similar results were achieved by adding to the same base composition inthe proportions indicated a solution of cyclohexadiene.

EXAMPLE l Perfume Composition of the Floral" Type A composition of the Floral type is prepared by admixing the following ingredients (parts by weight):

ill (It EXAMPLE 16 Preparation of a Flavouring Composition for Liqueurs of the Abbatial Type A flavouring composition destined for the preparation of liqueurs of the abbatial" (or chartreuse) type is prepared by admixing the following ingredients (parts by weight):

Neroli oil 5 Clove oil 20 Cardamom oil 25 Nutmeg oil 25 Cinnamon oil 25 Lemon oil 35 Sweet orange oil 65 Angelica grain oil 75 Peppermint oil 75 Bitter orange oil 200 Angelica root oil 45-5- Total 995 A test composition is prepared by the addition of 5 g of trans-2,6,6-trimethyl-l-[buten-2oyl]-2,4- cyclohexadiene to 995 g of the above mixture. The check mixture results from the addition of 5 g of Angelica root oil to 995 g of the above mixture.

A base for a liqueur is prepared by admixing the following ingredients in the doses indicated:

Edible alcohol, 96 (v/v) 325 ml Wine spirit, 74 l00 ml Sugar syrup, 65 ml Water 565 ml Total 1000 ml 2,6,6-trimethyl- 1 -[buten-3-oyl]-2,4-

The base is flavoured with 10 g of flavouring composition per 100 g of base. The prepared and finished liqueurs are tasted by a group of experts. All the members of the group have declared that the test" liqueur possessed a more rounded-off tast than that of the check liqueur.

EXAMPLE 17 Preparation of a flavouring composition of the Tutti; Frutti type A flavouring composition of the -Tutti-Frutti type was prepared by admixing the following ingredients (parts by weight):

Vanillin 20 Allyl caproate l0 Citral 2O Amyl butyrate 35 Orange oil 45 Ethyl butyrate Ethyl acetate 185 Amyl acetate 185 Lemon oil fill Total 975 25 g of trans-2,6,6-trimethyl-l-[buten-2-oyl]-2,4- cyclohexadiene were added to 975 g of the above mixture called test" composition. A check composition was prepared by the addition of i 25 g of lemon oil to 975 g of the above mixture.

The test and check compositions were added to the foodstuffs describedbel'ow in the indicated proportions kg of product to be flavoured) Candy: 100 ml of sugar syrup (obtained by dissolving one kilogram of sucrose in 600 ml of water) and 20 g of glucose were mixed and slowly heated to The flavour was added to the mass and the mixture was allowed to cool and harden.

Custard: A mixture of 60 g of sucrose and 3 g of pectin were added, while stirring, to 500 ml of warm milk. The mixture was brought to the boiling point for a few seconds and the flavour was added, whereupon the whole was cooled.

Cake: The following ingredients were mixed: 100 g of vegetable margarine, 1.5 g of NaCl, 100 g of sucrose, 2 eggs and 100 g of flour. The flavour was added to the above mass and the whole was heated to for 40 minutes.

The samples of finished foodstuff were tasted by a group of experts who had to state their opinion as to the taste of the samples which had been submitted to them. All the members of the group unanimously declared without any hesitation that the test" samples had a more marked fruity and woody note than that of the check samples and that they moreover possessed a character which was reminiscent of red berries.

Analogous results were obtained by replacing in the above example trans-2,6,6-trimethyl-l-[buten-2-oyl]- 2,4-cyclohexadiene by 2,6,6-trimethyl-l-[buten-3- oyl]-2,4-cyclohexadiene, cisand trans-Z-methylene- 6,6-dimethyll buten-2-oyl ]-3 -cyclohexene, 2- methylene-6,6-dimentyl-l-[buten-3-oyl1-3- cyclohexene, cisand trans-2,6,6-trimethyl-l-[buten-Z- oyl l ,4-cyclohexadiene or 2,6,6-trimethyll buten-3- oyl l ,4-cyclohexadiene.

EXAMPLE 18 ,A base flav ouring composition was prepared by ad mixing the following ingredients (parts by weight):

' in 95 k ethyl alcohol g of a solution at 1 percent of the above composition in 95 percent ethyl alcohol were sprayed on 100 g of a tobacco mixture of american blend" type (sample C or control). 7

A test" sample (T) was prepared by spraying on 100 g of a tobacco mixture of american blend type a flavouring composition prepared by adding to 99 g of the above base composition 1 g of 1,6,6-trimethyl-l- [buten-2-oyl]-2,4-cyclohexadiene.

The two tobacco samples thus prepared were used for the preparation of cigarettes the smoke of which was subsequently subjected to taste evaluation by a panel of trained tasters.

The taste and flavour of the cigarettes prepared with tobacco sample T was characterized by a burnt note and by a woody, herbal character reminiscent of hay. These latter features were not shown by the cigarettes prepared with tobacco sample C.

We claim:

1. Process for the preparation of compounds having the formula CO-O-ulkyl IIIa-l wherein the alkyl group is a lower alkyl group, which comprises treating a lower alkyl (1 isopropylidene acetoacetate in an inert organic solvent with at least one mol per mol of a compound resulting from the reaction of a quaternary phosphonium salt having the formula 1on CH crl PR3]+X- wherein R represents an alkyl or aryl radical and X represents a halogen, ClO or BF with a strong base.

2. Process according to claim 1, wherein the quaternary phosphonium salt is allyl triphenyl phosphonium chloride or bromide and the strong base is n-butyl or methyl lithium.

3. Process for preparing a compound which is a lower alkyl ester of 2,6,6 trimethyl l carboxy 2,4- cyclohexadiene which process comprises reacting together in hexane solution at from -20 C to +209 C at least one mol of allyl triphenyl phosphonium-chloride, bromide -or iodide per mole of a lower alkyl ester of alpha isopropylidene acetoacetic acid in the presence of n-butyl lithium or methyl lithium to yield a solution comprising said compound.

4. The process of claim 3 wherein said compound is obtained in pure form from said solution by conventional steps of extraction, washing, evaporation and chromatographic separation on an aluminacolumn.

5. The process of claim 4 wherein the purification steps comprise adding water to the hexane reaction mixture, separating the hexane phase, washing the hexane phase with water, evaporating the hexane to leave a solid residue, submitting the residue to successive extractions with hexane, passing the combined hexane extracts over a column of aluminum oxide to deliver a hexane eluate and evaporating the eluate to leave a crystalline substance corresponding to the composition 2, 6, 6 trimethyl 1 alkoxy carbonyl 2, 4 cyclohexadiene. 1

6. The process of' claim 4 wherein the purification steps comprise filtering the hexane reaction mixture to remove any solid precipitate and to leave a filtrate, washing the precipitate with hexane or ethyl ether or a mixture thereof to yield a second filtrate, combining the two filtrates, washing the combined filtrates with water, evaporating the washed filtrates to leave a dry solid residue, submitting this residue to successive extractions with hexane, passing the combined hexane extractsiover a column of aluminum oxide to deliver a hexane eluate and evaporating the eluate to leave a crystalline substance corresponding to the composition 2, 6, 6"trim'ethyl 1 alkoxycarbonyl 2, 4 cyclohexadi-. ene.

7. The process of claim 4 wherein the acetoacetate is ethyl alpha isopropylidene acetoacetate and the pure compound formed is 2, 6, 6 trimethyl l ethylcarbonyl 2,4 cyclohexadiene.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 890 ,370 DATED June 17, 1975 Page 1 of 3 INVVENTOR(S) GEORGE H. BfrcHI, ET AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 20 "constitute" should read reoonstitute.

Column 3 line 28 "tast" should read -taste.

Column 3, line 61 should read Column 3, line 64 "not" should read -note.

Column 7, line 9 "cornbrised" should read comprised-.

Column 13, line 23 "ethoxycarbonyl3" should read ethoxycarbonyl-3-.

Column 13, line 55 "32" should read Column 13, line 59 "a" should read -6.

Column 14 line 1 "readtion" should read reaction.

Column 14, line 40 "9318 Torr" should read 93/8 'Iorr-.

Column 14, line 44 "s" should read 6.

Column 14, line 45 "u" should read mu--.

Column 15, lines 11-12 "5% solution should read -5% aqueous solution-.

- Column 15, line 22 should read -m1i--.

Column 15, line 31 (CRDl should read (CDCl UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION 6 PATENT NO. 3 ,890 ,370

DATED June 17, 1975 Page 2 of 3 |NV ENTOR(S) GEORGE H. BficHI, ET AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: a

'. Column 15, line 45 "protions" should read portions.

Column 15 line 57 "u" should read -mu-.

Column 15, line 61 "2,4cyclohexadiene" should read --2,4cyclo hexadiene.

Column 15, line 62 "methylene6" should read -methylene6-.

Column 15, lines 64-65 "allylphenyl" should read --allylphenyl- Column 16, line 28 "u" should read --mu.

Column 16, line 46 "where" should read -were. D Column 16 line 59 "1680 1620" should read -l680 1650, l620.

Q Column 16, line 63 "um" should read mu(e--. Column 17, line 11 "u" should read -mu-. Column 17, line 17 "desdribed" should read described-. Column 17, line 20 "conbined" should read -combined-. i Column 17, line 32 "by a known methods" should read -by known methods-.

Column 17, line 43 "treeated" should read -treated-.

Column 17, line 45 "0.55" should read -o.o5-.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENTNO. I 3,890,370 DATED June '17, 1975 Page 3 of 3 INV ENTOR(S) GEORGE H. B jCHI, ET AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 17, line 55 "cm' should read -cm' Column 17, line 59 "22811 (=l2000) 255p (E=5000) 310p (t-:=2000)" should read 228mu (s=l2000) 255mm (s=5000) BlOmu (s=2000)--.

Column 18, line 1 "25 of" should read 25 ml of-.

Column 18, line 64 "cm"" should read cm' Column l8 line 68 "u" should read mu.

Column 19, line 38 "Anelica" should read Angelica-.

Column 19, line 62 "an" should read -An-.

Column 20, line 25 [buten-Z ,4" should read [buten-2-oyl] "2 ,4 l

Column 21, line 34 "similar" should read Similar-.

Column 22 line 5 "tast" should read taste.

Column 22, line 65 "6-dimentyl" should read -6-dimethyl--. Column 23, line 21 "1,6,6-trimethyl" should read 2,6,6 trimethyl-.

Signed and Scaled this second Day Of March1976 [SEAL] Attest:

RUTH C. MASON C MARSHALL DANN Attestmg Officer Commissioner ofPatents and Trademarks 

1. PROCESS FOR THE PREPARATION OF COMPOUNDS HAVING THE FORMULA
 2. Process according to claim 1, wherein the quaternary phosphonium salt is allyl triphenyl phosphonium chloride or bromide and the strong base is n-butyl or methyl - lithium.
 3. Process for preparing a compound which is a lower alkyl ester of 2,6,6 trimethyl - 1 carboxy 2,4- cyclohexadiene which process comprises reacting together in hexane solution at from -20* C to +20* C at least one mol of allyl triphenyl phosphonium chloride, bromide or iodide per mole of a lower alkyl ester of alpha -isopropylidene acetoacetic acid in the presence of n-butyl lithium or methyl lithium to yield a solution comprising said compound.
 4. The process of claim 3 wherein said compound is obtained in pure form from said solution by conventional steps of extraction, washing, evaporation and chromatographic separation on an alumina column.
 5. The process of claim 4 wherein the purification steps comprise adding water to the hexane reaction mixture, separating the hexane phase, washing the hexane phase with water, evaporating the hexane to leave a solid residue, submitting the residue to successive extractions with hexane, passing the combined hexane extracts over a column of aluminum oxide to deliver a hexane eluate and evaporating the eluate to leave a crystalline substance corresponding to the composition 2, 6, 6 trimethyl - 1 alkoxy carbonyl - 2, 4 - cyclohexadiene.
 6. The process of claim 4 wherein the purification steps comprise filtering the hexane reaction mixture to remove any solid precipitate and to leave a filtrate, washing the precipitate with hexane or ethyl ether or a mixture thereof to yield a second filtrate, combining the two filtrates, washing the combined filtrates with water, evaporating the washed filtrates to leave a dry solid residue, submitting this residue to successive extractions with hexane, passing the combined hexane extracts over a column of aluminum oxide to deliver a hexane eluate and evaporating the eluate to leave a crystalline substance corresponding to the composition 2, 6, 6 trimethyl - 1 alkoxycarbonyl - 2, 4 - cyclohexadiene.
 7. The process of claim 4 wherein the acetoacetate is ethyl alpha - isopropylidene acetoacetate and the pure compound formed is 2, 6, 6 trimethyl - 1 - ethylcarbonyl - 2,4 - cyclohexadiene. 